Mk25 S600

[Honkeye]

Hi all hope you can help. What would you say is the cause of the regulator 2nd stage going into freeflow, starting slowly so buble are trickling past your ears so you dont really notice eventually ending up with major free flow emptying cylinder in next to no time Octopus was not free flowing just the s600.
Water temp was not cold so freeze should not happen 7 degrees have used the regs in 2 degrees and did not freeze.
All the internals on the first stage have been changed but this happend again leading more to it being a second stage prob.
I belive Mike is the scubapro expert so what do you thing.

Cheers
honkeye

 

[devjr]

A first stage leak can easily be identified with a pressure gauge. Was this done before rebuilding it? Do you work for Apeks?

 

[Honkeye]

Hi I dont work for Apex or any other diving company just dive for fun. If it was the first stage leaking would it come from the first stage or would it not come from the octo and the main.

I did not do anything with the regs when they went wrong just gave it back to the LDS who sent it to Scubapro.

 

[devjr]

It sounds like freeze up. Does it freeflow out of the water, in warm environment? When you turn on air valve does reg freeflow immediately or after a few seconds have passed? Not at all? Only in water?

I can't think of much that would go wrong in 2nd stg except the poppet main spring or the balance valve. If the balance valve leaks it would be due to a bad O ring.

Clearly, the factory suspected a problem with the first stage. Either they found the problem or they didn't. However, even if not, they may have rebuilt it based on history of this type of reg. I don't know.

 

[Honkeye]

This does not happen when out the water, and when in the water it happend on the second dive so it does go for a while before going into free flow. I cant belive its freezing as the temp has been fine. As the first stage controlls air to both octo and main would not both go into free flow if its a problem on the first stage.
I know very little about how regs work.

 

[devjr]

Honkeye, that is sound reasoning. However, it would depend on the two 2nd stgs. The SP main second probably has a very low "cracking effort". If, due to a bad 1st stg, it flows first, the octo second might not freeflow at all. Also, if the octo is an "upstream" valve it will not freeflow at all. Does the flow stop if you turn the control knob?

The operation of the reg is fairly simple. The first stage is a pressure reducing valve which drops the tank press to about 145 psi.

The second stage is a demand valve which is opened by a diaphragm and lever when you inhale.

If the first stage leaks, the pressure in the air hose will rise causing the second to leak. This may take a few seconds until the line pressure rises enough to trigger the second stg valve.

 

[Honkeye]

Adjusting the cracking knob had no affect And as for checking if the pressure was fluttering i could not say as i was more concernd with getting to the surface.

SP have got the kit know and should get back with an answer mid week.
The first time they had the regs it was noticed that there was a slight water mark in the first stage and this was the cause of the flow problems?.

 

[devjr]

Yes, of course, the interstage pressure is normally checked out of the water. Sometimes a gauge is inserted directly into a LP port. There is also a gauge adapter which quick connects to a BC hose.

I'm stumped. A water mark would indicate a bad O ring. To have it happen twice would suggest something more fundamental. I would like to hear when you find out.

 

[Campana]

high pressure seat in the first stage is damaged or out of place, or high pressure piston is damaged where it hits the seat. There is a leak past the seat, and the pressure builds, and goes to the next lowest resistance point, the 600 second stage. When you took a breath did it stop for a second or two?

You may never find out, they'll just fix it and return it. If you do find out, let us know.

 

[Matt]

I would check the HP seat in the first stage. It could be indented. The second stage lever height could be too high, The Viva may also be on before you hit the water which will make it freeflow at times.

I would check the 2nd stage to make sure no water is leaking in, and maybe drop the intermediate pressure in the first stage if its higher than 140psi (approx 9.5bar). The LP seat may need to be flipped. Most likely the Lever height.

Ask your diveshop what to do, unless you want to send it to Canada where the shop I have here will fix.